CHICAGO (CBS/AP) — A young man from Illinois was among five U.S. Marines killed last week, when their refueling plane collided with a fighter jet off the southern coast of Japan.

Daniel Baker, 21, was among five crew members of a KC-140 Hercules refueling aircraft that collided with an F/A-18 Hornet during training on Dec. 6. Both planes crashed into the sea south of Japan’s Shikoku island.

Baker lived in Tremont, Illinois, just south of Peoria. Baker’s family said they are proud he joined the Marines, despite the risks.

“It’s a tragedy that no parent wants to go through. They’re in contact with the Marines daily,” said family spokesman Matt Miller.

Marine Cpl. Daniel Baker relaxes with his cousin Hazel during a visit to his home in Tremont, Illinois in June, 2018. Baker was among the five crew members aboard a KC-130J Hercules air refueler killed when it collided with an F/A-18 jet off the coast of Japan on Dec. 6. (Photo courtesy Matt Miller)

The Marine Corps identified the other four KC-140 crew members as Lt. Col. Kevin R. Herrmann, 38, of New Bern, North Carolina; Maj. James M. Brophy, 36, of Staatsburg, New York; Staff Sgt. Maximo A. Flores, 27, of Surprise, Arizona; and Cpl. William C. Ross, 21, of Hendersonville, Tennessee.

Their bodies have not yet been recovered.

One pilot of the fighter jet survived the crash. The other Hornet pilot, Capt. Jahmar Resilard, 28, of Miramar, Florida, was killed in the crash.

The Marines said that the two planes were involved in routine training, including aerial refueling, but that it was still investigating what caused the crash.

The crash is the latest in recent series of accidents involving the U.S. military deployed to and near Japan.

Last month, a U.S. Navy F/A-18 Hornet from the aircraft carrier USS Ronald Reagan crashed into the sea southwest of Japan’s southern island of Okinawa, though its two pilots were rescued safely. In mid-October, a MH-60 Seahawk also belonging to the Ronald Reagan crashed off the Philippine Sea shortly after takeoff, causing non-fatal injuries to a dozen sailors.

Two years ago, a MV-22 tilt-rotor aircraft Osprey crashed during a nighttime refueling exercise off the southern island of Okinawa, injuring two crew members.

More than 50,000 U.S. troops are based in Japan under a bilateral security pact.